JP6946964B2 - Robot joint structure - Google Patents

Description

The present invention relates to a robot joint structure, particularly a robot hand finger structure.

A robot hand that imitates a human hand has been developed to enable complicated work by a robot, and when a gripped member that is an object is gripped, the fingers of the robot hand fit into the outer shape of the gripped member. There is something that is done.

For example, the finger structure of the robot hand of Patent Document 1 includes a first finger plate, a second finger plate, and a third finger plate. The first finger plate and the second finger plate are rotatably connected via a torsion spring that exerts a restoring force on the side that extends as the finger bends. Further, the second finger plate and the third finger plate are also rotatably connected via a torsion spring that exerts a restoring force on the side that extends as the finger bends.

Such a finger structure operates so that, for example, when the first finger plate comes into contact with the gripped member while the finger is extended, the second finger plate and the third finger plate grip the gripped member. , The structure is such that the finger fits into the member to be gripped.

JP-A-2002-103269

In the finger structure of the robot hand of Patent Document 1, a first finger plate and a second finger plate, and a second finger plate and a second finger plate are provided by a torsion spring that exerts a restoring force on the side that extends as the finger bends. 3 finger plates are connected. Therefore, in order to grip the gripped member with the finger structure of the robot hand of Patent Document 1, a driving force that overcomes the restoring force of the torsion spring is required, and an actuator such as a servomotor for operating the finger becomes large. Have a task to do.

The present invention has been made in view of such problems, and realizes a robot joint structure that contributes to miniaturization of an actuator for operating a joint in the robot.

The joint structure of the robot according to one aspect of the present invention is
A first link that can be rotated around the first axis of rotation by an actuator,
A second link that can rotate about the first axis of rotation with respect to the first link,
A third link that can rotate about a second axis of rotation with respect to the first link,
A fourth link that is rotatable about a third rotation axis with respect to the second link and is rotatable about a fourth rotation axis with respect to the third link.
A robot joint structure comprising a four-node link mechanism in which the first rotation axis, the second rotation axis, the third rotation axis, and the fourth rotation axis are different from each other.
It comprises a first elastic member having one end fixed to the second link and the other end fixed to the third link.
When the extended state of the finger is set to the initial state, the first elastic member is extended as the finger is in the bent state, and the restoring force is increased.
In the initial state of the finger, on a plane orthogonal to the direction in which the first rotation axis extends, the center of the second rotation axis passes through the center of the second rotation axis, and the center of the second rotation axis and the fourth rotation axis. The distance between the second straight line orthogonal to the first straight line passing through the center of the rotation axis and the fixing point between the third link and the other end of the first elastic member is the first. A fourth straight line passing through the center of the rotation axis of the above and orthogonal to a third straight line passing through the center of the first rotation axis and the center of the third rotation axis, the second link, and the second. It is equal to or greater than the distance between the fixed point of 1 and the one end of the elastic member.
With such a configuration, when gripping the gripped member, a moment is given to the side gripping the gripped member by the first elastic member. Therefore, when gripping the gripped member, the restoring force of the first elastic member is added to the driving force of the actuator, and the gripped member can be gripped with a small driving force. As a result, it is possible to contribute to the miniaturization of the actuator for operating the joint in the robot.

In the joint structure of the robot, the first elastic member is preferably a resin ring member.
As a result, the installation space may be smaller and the cost is lower than when a coil spring or the like is used as the first elastic member.

In the above robot joint structure
A fifth link that can rotate about a fifth axis of rotation with respect to the third link,
A sixth link that is rotatable about a sixth rotation axis with respect to the fourth link and is rotatable about a seventh rotation axis with respect to the fifth link.
It is preferable to provide.
As a result, it is possible to realize a fine familiar operation with the member to be gripped.

In the above robot joint structure
A second elastic member having one end fixed to the fourth link and the other end fixed to the fifth link.
The second elastic member expands as the finger becomes bent, and the restoring force increases.
In the initial state of the finger, on a plane orthogonal to the direction in which the third rotation axis extends, the center of the third rotation axis passes through the center of the third rotation axis, and the center of the third rotation axis and the sixth rotation axis. The distance between the sixth straight line orthogonal to the fifth straight line passing through the center of the rotation axis and the fixing point between the fifth link and the other end of the second elastic member is the sixth. It is preferable that the distance between the straight line and the fixed point between the fourth link and one end of the second elastic member is equal to or greater than the distance between the straight line.
Thereby, when rotating the fourth link and the sixth link, the restoring force of the second elastic member can be added to the driving force of the actuator.

In the joint structure of the robot, the second elastic member is preferably a resin ring member.
As a result, the installation space may be smaller and the cost is lower than when a coil spring or the like is used as the second elastic member.

According to the present invention, it is possible to contribute to the miniaturization of the actuator for operating the joint in the robot.

It is a perspective view which shows typically the initial state of the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is an exploded view of the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure for demonstrating the familiar operation at the time of grasping a member to be grasped with the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure for demonstrating the familiar operation at the time of grasping a member to be grasped with the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure for demonstrating the familiar operation at the time of grasping a member to be grasped with the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure for demonstrating the familiar operation at the time of grasping a member to be grasped with the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure which shows the mechanical property of the elastic member at the time of grasping the gripped member by the finger which adopted the finger structure of the robot hand of Patent Document 1. FIG. It is a figure which shows the mechanical property of the elastic member at the time of grasping the gripped member by the finger which adopted the joint structure of the robot of Embodiment 1. FIG. It is a figure for demonstrating the function of the restoring force of the elastic member of Embodiment 1. FIG. It is a figure which shows the mechanical property of the elastic member at the time of grasping the gripped member by the finger which adopted the joint structure of the robot of Embodiment 2. FIG. It is a figure which shows typically the structure of the robot hand of Embodiment 3. It is a figure which shows typically the index finger of the robot hand of Embodiment 3. It is a figure for demonstrating the arrangement of the elastic member of the index finger of the robot hand of Embodiment 3. FIG. It is a figure which shows typically the thumb of the robot hand of Embodiment 3. It is an enlarged view of the XV part of FIG.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Further, in order to clarify the explanation, the following description and drawings have been simplified as appropriate.

<Embodiment 1>
First, the configuration of a finger adopting the joint structure of the robot of the present embodiment will be described. FIG. 1 is a perspective view schematically showing an initial state of a finger adopting the joint structure of the robot of the present embodiment. FIG. 2 is an exploded view of a finger adopting the joint structure of the robot of the present embodiment.

The joint structure of the robot of the present embodiment can be suitably adopted for, for example, the fingers of a robot hand that imitates a human hand. As shown in FIGS. 1 and 2, the finger 1 adopting the joint structure of the robot of the present embodiment has a first link 2, a second link 3, a third link 4, and a fourth link 5. An elastic member 8 such as a fifth link 6, a sixth link 7, and a coil spring is provided, and is rotatably connected to a palm portion (not shown).

Here, in the following description, in order to clarify the explanation, the configuration of the finger 1 in the initial state in which the finger 1 is in the extended state will be described using a three-dimensional (XYZ) coordinate system. The X-axis − side is the base side of the finger 1, and the X axis + side is the tip side of the finger 1. The Z-axis-side is the palm side, and the Z-axis + side is the back side of the hand.

The first link 2 is a driving node that is rotationally driven by an actuator (not shown) such as a servomotor provided on the palm. For example, the first link 2 has a substantially rectangular plate member having a thin thickness in the Y-axis direction and a large ratio of the longitudinal length to the lateral length in the XZ plane as a basic form. On the other hand, it is inclined to the Z-axis + side by about 30 °. The first link 2 includes a first rotation shaft 2a projecting from one end of the first link 2 to the Y-axis + side. The first rotary shaft 2a is connected to the rotary shaft of the actuator so that the rotary torque can be transmitted from the actuator.

The first link 2 includes a second rotating shaft 2b that projects from the other end of the first link 2 to the Y-axis − side. Such a first link 2 rotates around the first rotation shaft 2a by transmitting the rotation torque of the actuator to the first rotation shaft 2a.

The second link 3 is rotatably connected to the first link 2 around the first rotation shaft 2a provided on the first link 2. For example, the second link 3 is based on a substantially rectangular plate member having a thin thickness in the Y-axis direction and a large ratio of the longitudinal length to the lateral length in the XZ plane. The longitudinal direction of the link 3 extends in the substantially X-axis direction.

The second link 3 is provided with a first through hole 3a at one end of the second link 3, and the first rotation shaft 2a of the first link 2 is provided in the first through hole 3a. Is passed through. The second link 3 is provided with a second through hole 3b at the other end of the second link 3.

The third link 4 is rotatably connected to the first link 2 around the second rotation shaft 2b provided on the first link 2. For example, the third link 4 is substantially parallel to the second link 3 when viewed from the Y-axis direction, and is arranged slightly on the Z-axis + side with respect to the second link 3. The third link 4 is arranged so as to sandwich the first link 2 between the third link 4 and the second link 3 when viewed from the Z-axis direction.

The third link 4 is based on a substantially rectangular plate member having a thin thickness in the Y-axis direction and a large ratio of the longitudinal length to the lateral length in the XZ plane, and is X in the longitudinal direction. The axial length is substantially equal to that of the second link 3. The third link 4 is provided with a first through hole 4a at one end of the third link 4, and the second rotation of the first link 2 is provided in the first through hole 4a. The shaft 2b is passed through. Further, the third link 4 includes a rotation shaft 4b protruding from the other end of the third link 4 to the Y-axis + side.

The fourth link 5 is rotatable about the rotation axis 5d provided on the fourth link 5 with respect to the second link 3, and is provided on the third link 4 with respect to the third link 4. It is rotatably connected around the rotating shaft 4b. For example, the fourth link 5 is arranged between the second link 3 and the third link 4 when viewed from the Z-axis direction.

The fourth link 5 has a basic form of a plate member that is thin in the Y-axis direction and bends when viewed from the Y-axis direction, as will be described in detail later. I have. The first portion 5a has a length substantially equal to that of the first link 2, and is arranged substantially parallel to the first link 2 when viewed from the Y-axis direction.

Specifically, in the fourth link 5, the first portion 5a is on the Z-axis + side of about 30 ° with respect to the second portion 5b at the bending starting point portion of the first portion 5a and the second portion 5b. It is bent to. The fourth link 5 is provided with a first through hole 5c at the tip of the first portion 5a, and the rotation shaft 4b of the third link 4 is passed through the first through hole 5c. .. Further, the fourth link 5 is provided with a rotation shaft 5d projecting to the Y-axis + side at the bending starting point. The rotating shaft 5d is passed through the second through hole 3b of the second link 3.

As a result, the first link 2, the second link 3, the third link 4, and the first portion 5a of the fourth link 5 form a four-section parallel link mechanism 9. As the parallel link mechanism 9 rotates, the second portion 5b of the fourth link 5 rotates around the rotation axis 5d. The second portion 5b extends substantially in the X-axis direction, and is provided with a second through hole 5e at the tip end portion of the second portion 5b.

However, in the present embodiment, the first link 2, the second link 3, the third link 4, and the first portion 5a of the fourth link 5 are the parallel link mechanism 9 of section 4. However, the first link 2, the second link 3, the third link 4, and the first part 5a of the fourth link 5 form a closed link. It may be a mechanism.

The fifth link 6 is rotatably connected to the third link 4 around the first rotation shaft 6a provided on the fifth link 6. For example, the fifth link 6 is arranged slightly on the Z-axis + side with respect to the fourth link 5 when viewed from the Y-axis direction, and the Y-axis-with respect to the third link 4 when viewed from the Z-axis direction. It is located on the side.

The fifth link 6 has a substantially rectangular plate member having a thin thickness in the Y-axis direction and a large ratio of the longitudinal length to the lateral length in the XZ plane as a basic form. The fifth link 6 is provided with a first rotating shaft 6a projecting to the Y-axis + side at one end of the fifth link 6, and the first rotating shaft 6a is a third. It is passed through a second through hole 4d formed in a protruding portion 4c protruding to the Z-axis + side of the link 4. Further, the fifth link 6 is provided with a second rotating shaft 6b projecting to the Y-axis + side at the other end of the fifth link 6.

The sixth link 7 is rotatable about the rotation axis 7d provided on the sixth link 7 with respect to the fourth link 5, and is provided on the fifth link 6 with respect to the fifth link 6. It is rotatably connected around the second rotating shaft 6b. For example, the sixth link 7 is arranged between the fourth link 5 and the fifth link 6 when viewed from the Z-axis direction.

The sixth link 7 has a basic form of a plate member that is thin in the Y-axis direction and bends when viewed from the Y-axis direction, as will be described in detail later. I have. The first portion 7a has a length substantially equal to that of the first link 2, and is arranged substantially parallel to the first link 2 when viewed from the Y-axis direction. The second portion 7b extends substantially in the X-axis direction.

That is, in the sixth link 7, the first portion 7a is bent to the Z-axis + side by about 30 ° with respect to the second portion 7b at the bending starting point portion of the first portion 7a and the second portion 7b. doing. The sixth link 7 is provided with a through hole 7c at the tip of the first portion 7a, and the second rotation shaft 6b of the fifth link 6 is passed through the through hole 7c. Further, the sixth link 7 is provided with a rotation shaft 7d projecting to the Y-axis + side at the bending starting point. The rotating shaft 7d is passed through the second through hole 5e of the fourth link 5.

In the initial state of such a first link 2, a second link 3, a third link 4, a fourth link 5, a fifth link 6 and a sixth link 7, the first link 2 is used. _{The center O 1} of the first rotation axis 2a of the first link 2, which is the rotation axis of the second link 3, and _{the center O 2} of the rotation axis 5d of the fourth link 5 with respect to the second link 3. the center O ₃ of the rotary shaft 7d of the sixth link 7 relative to the fourth link 5, but is disposed substantially on the X axis.

Then, in the initial state of the first link 2, the second link 3, the third link 4, the fourth link 5, the fifth link 6 and the sixth link 7, the Z in the second link 3 The axis-side side, the Z-axis-side side of the second portion 5b in the fourth link 5, and the Z-axis-side side of the second portion 7b in the sixth link 7 are approximately X. Placed on the axis.

That is, in the initial state of the first link 2, the second link 3, the third link 4, the fourth link 5, the fifth link 6 and the sixth link 7, the second link 3 and The second portion 5b of the fourth link 5 and the second portion 7b of the sixth link 7 are arranged substantially straight in the X-axis direction. Here, the second link 3 forms the proximal phalanx of the finger 1, the second portion 5b of the fourth link 5 forms the middle phalanx of the finger 1, and the second link 7 of the sixth link 7. Part 7b forms the end section.

The elastic member 8 is, for example, a coil spring. One end of the elastic member 8 is fixed to the second link 3. The other end of the elastic member 8 is fixed to the third link 4. Such an elastic member 8 is formed on the notch portion 3c formed on the Z-axis + side side of the second link 3 and on the Z-axis − side side of the third link 4 when viewed from the Y-axis direction. It is housed in the formed notch portion 4e. However, the elastic member 8 is not limited to the coil spring, and may be another elastic member, and a tension spring, a torsion spring, or the like can also be used.

Here, the elastic member 8 of the present embodiment will be described in detail later, but in the initial state of the finger 1, the XZ is extended so that the restoring force increases as the finger 1 changes from the initial state to the bent state. _{On a plane, it passes through the center O 4} of the second rotation axis 2b of the first link 2, which is the rotation axis of the third link 4 with respect to the first link 2, and the center O ₄ and the third link 4 A second straight line L _{2 orthogonal to the first} straight line L _{1 passing through the center O 5} of the rotation axis 4b of the third link 4, which is the rotation axis of the fourth link 5, and the other of the elastic members 8. the a fixed point J ₁ of the end portion and the third link 4, the distance R ₁ of the passes through the center O _1, to and perpendicular to the center O ₁ and the center O ₂ and the third straight line L ₃ through the It is arranged so that the distance R ₂ or more between the straight line L _{4 of 4 and the fixed point J 2} between one end of the elastic member 8 and the second link 3 (see FIG. 3). That is, in the initial state of the finger 1, the elastic member 8 is inclined to the X-axis + side with respect to the first link 2.

Next, a familiar operation when the gripped member is gripped by the finger 1 adopting the joint structure of the robot of the present embodiment will be described. Here, the familiar operation means that the finger 1 operates so as to imitate the outer shape of the member to be gripped. In the following description, in the illustration of FIGS. 3 to 6, the counterclockwise rotation direction of the link will be the positive direction, and the clockwise rotation direction will be the negative direction.

3 to 6 are views for explaining a familiar operation when the gripped member is gripped by a finger adopting the joint structure of the robot of the present embodiment. As shown in FIG. 3, the initial state of the finger 1 is the state in which the finger 1 is extended in the X-axis + direction. Next, the actuator (servomotor) is driven to rotate the first link 2 in the positive direction around the first rotation axis 2a of the first link 2. That is, with the finger 1 extended, the finger 1 is rotated around the first rotation axis 2a so as to be closer to the side of the member to be gripped 10. Then, as shown in FIG. 4, the second link 3 comes into contact with the gripped member 10.

When the actuator is further driven from this state, as shown in FIG. 5, the operation of the second link 3 is restricted by the gripped member 10, that is, the second link 3 becomes a stationary node. In this state, the parallel link mechanism 9 rotates in the positive direction. As a result, the second portion 5b of the fourth link 5 rotates in the positive direction around the rotation axis 5d of the fourth link 5 and approaches the gripped member 10, and the rotation axis of the sixth link 7 The second portion 7b of the sixth link 7 rotates in the positive direction around 7d and approaches the gripped member 10.

Then, when the actuator is further driven, as shown in FIG. 6, the parallel link mechanism 9 rotates in the positive direction in a state where the second link 3 is a stationary node. As a result, the second portion 5b of the fourth link 5 rotates in the positive direction around the rotation axis 5d of the fourth link 5, comes into contact with the gripped member 10, and rotates the sixth link 7. The second portion 7b of the sixth link 7 rotates in the positive direction around the shaft 7d and comes into contact with the gripped member 10. As a result, the finger 1 can be adapted to the outer shape of the gripped member 10.

In such a familiar operation of the finger 1, as described above, the elastic member 8 expands as the finger 1 changes from the initial state to the bent state, and the restoring force increases. That is, the elastic member 8 urges the familiar operation of the finger 1 on the side where the finger 1 grips the member 10 to be gripped.

Next, the function of the restoring force of the elastic member 8 when the gripped member 10 is gripped by the finger 1 adopting the joint structure of the robot of the present embodiment will be described. First, as a comparative example, the function of the restoring force of the elastic member 101 when the gripped member 10 is gripped by the finger 100 adopting the finger structure of the robot hand of Patent Document 1 will be described. FIG. 7 is a diagram showing the mechanical properties of the elastic member when the gripped member is gripped by a finger adopting the finger structure of the robot hand of Patent Document 1.

Here, the finger 100 of Patent Document 1 is described in order to make it easier to understand the difference between the mechanical characteristics of the elastic member 8 of the finger 1 of the present embodiment and the mechanical characteristics of the elastic member 101 of the finger 100 of Patent Document 1. A link structure equivalent to the link structure of the finger 1 of the embodiment is adopted, and the arrangement of the elastic members 101 is different. Therefore, in FIG. 7, a reference numeral equal to the link corresponding to the finger 1 of the present embodiment is attached.

In the finger 100 of Patent Document 1, as shown in FIG. 7, the elastic member 101 is formed at one end of the second link 3 so as to exert a restoring force on the extension side of the finger 100. It is arranged between the portion 3d and the palm portion 102.

_{The moment t 12} around the first rotation axis 2a of the first link 2 when the gripped member 10 is gripped by the palm portion 102 by using the finger 100 of Patent Document 1 is described in the following <Equation 1 Can be represented by>.
<Equation 1> t ₁₂ = -fr
Where, f is the restoring force of the elastic member 101, r is in a direction perpendicular to the stretching direction of the elastic member 101, the center O _1, an elastic member 101 of the projecting portion 3d of the second link 3 This is the distance between the fixed point j and the fixed point j.

Such a moment t ₁₂ acts in the opposite direction to the driving force P of the actuator. Therefore, when the driving force P by the actuator is applied to the finger 100, the moment given by the finger 100 to the gripped member 10 can be expressed by the following <Equation 2>.
<Equation 2> P + t ₁₂ = P-fr

FIG. 8 is a diagram showing the mechanical characteristics of the elastic member when the gripped member is gripped by a finger adopting the joint structure of the robot of the present embodiment. FIG. 9 is a diagram for explaining the function of the restoring force of the elastic member of the present embodiment. Incidentally, in FIG. 9, the state of the finger 1 in FIG. 5 is shown by a solid line, and in the state of the finger 1 in FIG. 5, the gripped member 10 is removed, and the finger 1 is extended by the restoring force of the elastic member 8. Is indicated by a alternate long and short dash line.

As shown in FIG. 8, when the gripped member 10 is gripped by the palm portion 11 using the fingers 1 of the present embodiment, the moment T ₁₂ around the first rotation axis 2a of the first link 2 is set. It can be expressed by the following <Equation 3>.
<Equation 3> T ₁₂ = F _c (R _3- R ₂ )
However, F _c is a component force in the direction orthogonal to _{the third straight line L 3} in the restoring force F of the elastic member 8. Further, R ₃ is an interval between the fourth straight line L ₄ and the fixed point J _1.

_{Since the finger 1 of the present embodiment has a relationship of R 1} > R ₂ in the initial state of the finger 1 as described above, when the first link 2 is rotated around the first rotation axis 2a, The relationship of R ₃ > R ₂ is established, and a moment in the direction of pressing the finger 1 against the gripped member 10 is generated during the familiar operation of the finger 1. That is, as shown in FIG. 9, the elastic member 8 exerts a restoring force on the finger 1 to return the finger 1 to the extended state. Therefore, when the driving force P by the actuator is applied to the finger 1, the moment given by the finger 1 to the gripped member 10 can be expressed by the following <Equation 4>.
<Equation 4> P + T ₁₂ = P + F _c (R _3- R ₂ )

As described above, when the finger 100 of Patent Document 1 is gripped by the gripped member 10, a moment is given to the side opposite to the side gripping the gripped member 10 by the elastic member 101. Therefore, when the gripped member 10 is gripped by the finger 100, the restoring force of the elastic member 101 is subtracted from the driving force P of the actuator. Therefore, a driving force P that overcomes the restoring force of the elastic member 101 is required, and the actuator for operating the finger 100 becomes large.

On the other hand, in the finger 1 of the present embodiment, when the gripped member 10 is gripped, a moment is given to the side gripping the gripped member 10 by the elastic member 8. Therefore, when the gripped member 10 is gripped by the finger 1, the restoring force of the elastic member 8 is added to the driving force P of the actuator. Therefore, the gripped member 10 can be gripped with a small driving force P with respect to the finger 100 of Patent Document 1. As a result, the joint structure of the robot adopted by the finger 1 of the present embodiment can contribute to the miniaturization of the actuator, and accordingly, for example, the robot hand can be inexpensively configured and the weight can be reduced.

Further, the finger 1 of the present embodiment can exert a large gripping force when an equal driving force is applied by the actuator as compared with the finger 100 of Patent Document 1, and can firmly grip the gripped member 10. ..

<Embodiment 2>
In the first embodiment, the familiar operation of the finger 1 when the second link 3 comes into contact with the gripped member 10 has been described, but the second portion 5b of the fourth link 5 comes into contact with the gripped member 10. In this case, the familiar operation can be realized in the same way.

FIG. 10 is a diagram showing the mechanical characteristics of the elastic member when the gripped member is gripped by a finger adopting the joint structure of the robot of the present embodiment. In addition, in FIG. 10, the state of the finger 1 immediately after the second portion 5b of the fourth link 5 comes into contact with the gripped member 10 is shown by a alternate long and short dash line, and the actuator 1 is further driven to drive the finger 1 in a familiar operation. The state is shown by a solid line.

As shown in FIG. 10, when the gripped member 10 is gripped by the palm portion 11 using the fingers 1 of the present embodiment, the force F _t acting on the gripped member 10 from the fingers 1 is expressed by the following <formula. It can be represented by 5>.
<Equation 5> F _t = R ₄ (P + T ₁₂ ) = R ₄ (P + Fc (R _3- R ₂ ))
However, R ₄ is the distance between the center O ₁ and the contact point C where the second portion 5b of the fourth link 5 comes into contact with the gripped member 10.

At this time, the force F _t acts in the tangential direction of the circle having the center O ₁ and the contact point C at both ends of the diameter, and acts on the side of the member to be gripped 10. Therefore, even in the present embodiment, the restoring force of the elastic member 8 is added to the driving force P of the actuator, and the gripped member 10 is gripped with a small driving force P with respect to the finger 100 of Patent Document 1. be able to.

By the way, when the actuator is further driven, the fourth link 5 rotates in the positive direction around the rotation axis 5d from the state of the finger 1 in FIG. 10, and the gripped member 10 is pulled up to the side of the second link 3. The sixth link 7 rotates in the forward direction around the rotation axis 7d and fits into the gripped member 10. Finally, the second link 3, the second portion 5b of the fourth link 5, and the second portion 7b of the sixth link 7 come into contact with the gripped member 10 and finger. 1 can be adapted to the gripped member 10.

In the first and second embodiments described above, the second link 3, the second portion 5b of the fourth link 5, and the second portion 7b of the sixth link 7 are the initial stages of the finger 1. Although it is arranged substantially straight in the state, it may be slightly bent.

Further, the shape and arrangement of the respective links 2, 3, 4, 5, 6 and 7 are not limited. Further, the relationship between the rotation shaft and the through hole is not limited. In short, the second link 3 is rotatable with respect to the first link 2, the third link 4 is rotatable with respect to the first link 2, and the second and third links are rotatable. The fourth link 5 is rotatable relative to 4, the fifth link 6 is rotatable relative to the third link 4, and the sixth link 5 is rotatable relative to the fourth link 5 and the fifth link 6. It suffices if the link 7 of is rotatable. Then, in the initial state of the finger 1, it is sufficient that the relationship _{of the interval R 1} > R _{2 is satisfied.}

Here, the fifth link 6 and the sixth link 7 may be omitted, but if the fifth link 6 and the sixth link 7 are provided, they are finely familiar with the gripped member 10. The operation can be realized.

<Embodiment 3>
FIG. 11 is a diagram schematically showing the configuration of the robot hand of the present embodiment. FIG. 12 is a diagram schematically showing the index finger of the robot hand of the present embodiment. FIG. 13 is a diagram for explaining the arrangement of the elastic member of the index finger of the robot hand of the present embodiment. FIG. 14 is a diagram schematically showing the thumb of the robot hand of the present embodiment. FIG. 15 is an enlarged view of the XV portion of FIG.

As shown in FIG. 11, the robot hand 30 of the present embodiment includes a palm portion 31, a index finger 32, a middle finger 33, a ring finger 34, a little finger 35, and a thumb finger 36, and the respective fingers 32, 33, 34, respectively. 35 and 36 adopt the finger structure of the robot hand of the first embodiment. Incidentally, although the palm portion 31 shown in FIG. 11 constitutes the back of the hand, it may also form the palm.

Here, since the index finger 32, the middle finger 33, the ring finger 34, and the little finger 35 have substantially the same configuration except for the length of the link, the index finger 32 will be described as a representative. As shown in FIG. 12, the index finger 32 of the present embodiment has a first link 41, a second link 42, a third link 43, a fourth link 44, a fifth link 45, and a sixth link. 46, a first elastic member 47 and a second elastic member 48 are provided, and the connection relationship is substantially the same as that of each link of the finger 1 of the first embodiment.

That is, the first link 41 corresponds to the first link 2 of the finger 1 of the first embodiment, and the second link 42 corresponds to the second link 3 of the finger 1 of the first embodiment. The third link 43 corresponds to the third link 4 of the finger 1 of the first embodiment, and the fourth link 44 corresponds to the fourth link 5 of the finger 1 of the first embodiment. The fifth link 45 corresponds to the fifth link 6 of the finger 1 of the first embodiment, and the sixth link 46 corresponds to the sixth link 7 of the finger 1 of the first embodiment.

However, the first link 41 of the present embodiment constitutes a bevel gear with the pinion gear 51 of the actuator 50. That is, the first link 41 is a disk-shaped gear gear having teeth formed along the peripheral edge of the side surface. Then, one end of the second link 42 is rotatably connected to the first rotation shaft 41a fixed to the substantially center of the first link 41. Further, one end of the third link 43 is rotatably connected to the side surface of the first link 41 via a second rotating shaft 41b provided on the first link 41.

In the present embodiment, the first link 41 is rotated by the rotational drive of the actuator 50, but the first link 41 may be rotated by the linear drive of the linear actuator. Further, the driving force of the actuator 50 may be transmitted to the first link 41 by using a wire, a timing belt, or the like.

The first elastic member 47 is, for example, a ring member made of resin such as rubber, and is hung on a second link 42 and a third link 43. Since the first elastic member 47 is made of a resin ring member in this way, the installation space may be narrower than when a coil spring or the like is used as the first elastic member 47, and the installation space may be smaller. , Cheap. At this time, it is preferable that the second link 42 and the third link 43 are formed with notches for hooking and fixing the first elastic member 47.

Here, since the indicator finger 32 has a configuration substantially equal to that of the finger 1 of the first embodiment, the arrangement of the first elastic member 47 will be described in place of the configuration of the finger 1 of the first embodiment. as shown, in the initial state of the index finger 32, on the XZ plane, the center O ₆ of the second rotation shaft 41b of the first link 41 is a rotary shaft of the third link 43 to the first link 41 as, the to and orthogonal center O ₆ and the first straight line L ₅ which passes through the center O ₇ of the rotary shaft 43b of the third the third for the link 43, which is the rotating shaft of the fourth link 44 of the link 43 and second linear _{L 6,} and the fixed point _{J 3} of the third link 43 of the first elastic member 47, the distance _{R 5} of a rotary shaft of the second link 42 relative to the first link 41 the A third straight line passing through the _{center O 8} of the first rotating shaft 41a of the first link 41 and passing through the center O _{8 and the center O 9} of the rotating shaft 44a of the fourth link 44 with respect to the second link 42. The distance between the fourth straight line L ₈ orthogonal to L ₇ and the fixed point J ₄ between the second link 4 2 in the first elastic member 47 is _{R 6} or more. That is, in the initial state of the index finger 32, the first elastic member 47 is inclined to the X-axis + side with respect to the first link 41. As a result, the restoring force of the first elastic member 47 can be added to the driving force P of the actuator when the index finger 32 is bent, as in the first embodiment.

The second elastic member 48 is, for example, a ring member made of resin such as rubber, and is hung on a fourth link 44 and a fifth link 45. At this time, as shown in FIG. 13, in the initial state of the index finger 32, on the XY plane, through the center _{O 9,} and the center of the rotation shaft 46a of the sixth link 46 center _{O 9} and for the fourth link 44 The distance R ₇ between the sixth straight line L ₁₀ orthogonal to the fifth straight line L ₉ passing through O _{10 and the fixed point J 5} between the fifth link 45 in the second elastic member 48 is the sixth. The distance between the straight line L _{10 and the fixed point J 6} between the straight line L 10 and the fourth link 44 in the second elastic member 48 is _{R 8} or more. That is, in the initial state of the index finger 32, the fixed point J ₅ is generally arranged on the fingertip side of the index finger 32 with respect to the fixed point J _6.

As a result, the second elastic member 48 also expands and the restoring force increases as the index finger 32 changes from the initial state to the bent state in the familiar operation of the index finger 32, similarly to the first elastic member 47. Therefore, when rotating the fourth link 44 and the sixth link 46, the restoring force of the second elastic member 48 can be added to the driving force P of the actuator.

Moreover, since the second elastic member 48 is also made of a resin ring member, the installation space may be narrower than when a coil spring or the like is used as the second elastic member 48, and the installation space may be smaller. It's cheap. At this time, it is preferable that the fourth link 44 and the fifth link 45 are formed with notches for hooking and fixing the second elastic member 48.

The first elastic member 47 and the second elastic member 48 are not limited to the resin ring member, and may be a coil spring or the like as in the first embodiment. Further, the first elastic member 47 and the second elastic member 48 are not limited to rubber, and may be any member that exhibits a restoring force. However, the second elastic member 48 may be omitted.

As shown in FIG. 14, the thumb 36 includes a base 61, a first link 62, a second link 63, a third link 64, a fourth link 65, and an elastic member 66. The base portion 61 is rotatably connected to the palm portion 31 via a rotation shaft 67 for inverting and abducting the thumb 36. The rotary shaft 67 is connected to the first actuator 68 so that rotational torque can be transmitted from the first actuator 68. When the first actuator 68 is driven, the thumb 36 inverts and abducts around the rotary shaft 67. .. As a result, the thumb 36 can be made to face the index finger 32 and the like.

The first link 62 is formed in a disk shape and rotates around a first rotation shaft 62a fixed at substantially the center of the first link 62 based on the rotational torque of the second actuator 69. The second link 63 corresponds to the second link 3 of the finger 1 of the first embodiment and forms the proximal phalanx of the thumb 36. Then, one end of the second link 63 is rotatably connected to the first rotation shaft 62a of the first link 62.

The third link 64 corresponds to the third link 4 of the finger 1 of the first embodiment, and one end of the third link 64 is a second rotating shaft provided on the first link 62. It is rotatably connected to the side surface of the first link 62 via 62b. The fourth link 65 corresponds to the sixth link 7 of the finger 1 of the first embodiment and forms the last node of the thumb 36. Then, the fourth link 65 is rotatably connected to the other end of the second link 63 via a rotation shaft 65a provided on the fourth link 65, and is also connected to the third link 64. It is rotatably connected to the other end of the third link 64 via a rotating shaft 64a provided.

Since such a robot hand 30 adopts the same arrangement of elastic members as in the first embodiment and constitutes each finger 32, 33, 34, 35, 36, the actuator is as in the first embodiment. It can contribute to the miniaturization of the 50 and the second actuator 69, and accordingly, the robot hand 30 can be miniaturized and lightened.

Here, the ring finger 34 and the little finger 35 of the present embodiment may be operated based on the driving force of one actuator 50. Specifically, as shown in FIG. 15, the first rotating shaft 41a of the first link 41 in the ring finger 34 and the first rotating shaft 41a of the first link 41 in the little finger 35 are interposed through the universal joint 70. Is connected.

As a result, the ring finger 34 and the little finger 35 can be operated based on the driving force of one actuator 50, and the robot hand 30 can be further reduced in size and weight. At this time, the ring finger 34 and the little finger 35 can be individually imitated with respect to the member to be gripped by the link structure.

The index finger 32, the middle finger 33, the ring finger 34, and the little finger 35 may also have a configuration capable of adduction and abduction like the thumb 36.

Further, the robot hand 30 of the present embodiment is configured to include the index finger 32, the middle finger 33, the ring finger 34, the little finger 35, and the thumb 36, but the number of fingers is not limited.

The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit.
The robot joint structure of the above embodiment is adopted for the fingers of the robot hand, but is not limited to this, and can be adopted for the joint portion of the robot.

1 Finger 2 1st link, 2a 1st rotation axis, 2b 2nd rotation axis 3 2nd link, 3a 1st through hole, 3b 2nd through hole, 3c notch 4 3rd link 4, 4a 1st through hole, 4b rotating shaft, 4c overhang, 4d 2nd through hole, 4e notch 5 4th link, 5a 1st part, 5b 2nd part, 5c 1st through Hole, 5d rotation shaft, 5e second through hole 6 fifth link, 6a first rotation shaft, 6b second rotation shaft 7 sixth link, 7a first part, 7b second part, 7c Through hole, 7d rotating shaft 8 elastic member 9 parallel link mechanism 10 gripped member 11 palm part 30 robot hand 31 palm part 32 indicator 33 middle finger 34 ring finger 35 small finger 36 thumb finger 41 first link, 41a first rotating shaft, 41b 2nd rotating shaft 42 2nd link 43 3rd link, 43b rotating shaft 44 4th link, 44a rotating shaft 45 5th link 46 6th link, 46a rotating shaft 47 1st elastic member 48 Second elastic member 50 Actuator 51 Pinion gear 61 Base 62 First link, 62a First rotation shaft, 62b Second rotation shaft 63 Second link 64 Third link, 64a Rotation shaft 65 Fourth link , 65a Rotating shaft 66 Elastic member 67 Rotating shaft 68 First actuator 69 Second actuator 70 Universal joint

Claims (3)

A first link that can be rotated around the first axis of rotation by an actuator,
A second link that can rotate about the first axis of rotation with respect to the first link,
A third link that can rotate about a second axis of rotation with respect to the first link,
A fourth link that is rotatable about a third rotation axis with respect to the second link and is rotatable about a fourth rotation axis with respect to the third link.
A robot joint structure comprising a four-node link mechanism in which the first rotation axis, the second rotation axis, the third rotation axis, and the fourth rotation axis are different from each other.
A first elastic member whose one end is fixed to the second link and whose other end is fixed to the third link .
A fifth link that can rotate about a fifth axis of rotation with respect to the third link,
A sixth link that is rotatable about a sixth rotation axis with respect to the fourth link and is rotatable about a seventh rotation axis with respect to the fifth link.
A second elastic member whose one end is fixed to the fourth link and whose other end is fixed to the fifth link.
Have,
When the extended state of the finger is set to the initial state, the first elastic member is extended as the finger is in the bent state, and the restoring force is increased.
In the initial state of the finger, on a plane orthogonal to the direction in which the first rotation axis extends, the center of the second rotation axis passes through the center of the second rotation axis, and the center of the second rotation axis and the fourth rotation axis. The distance between the second straight line orthogonal to the first straight line passing through the center of the rotation axis and the fixing point between the third link and the other end of the first elastic member is the first. A fourth straight line passing through the center of the rotation axis of the above and orthogonal to a third straight line passing through the center of the first rotation axis and the center of the third rotation axis, the second link, and the second. a fixed point and one end of the first elastic member state, and are more intervals,
The second elastic member expands as the finger becomes bent, and the restoring force increases.
In the initial state of the finger, on a plane orthogonal to the direction in which the third rotation axis extends, the center of the third rotation axis passes through the center of the third rotation axis, and the center of the third rotation axis and the sixth rotation axis. The distance between the sixth straight line orthogonal to the fifth straight line passing through the center of the rotation axis and the fixing point between the fifth link and the other end of the second elastic member is the sixth. line and, the one fixed point of the end of the fourth link and the second elastic member, Ru der above interval, articulated structure of the robot. The robot joint structure according to claim 1, wherein the first elastic member is a resin ring member. The robot joint structure according to claim 1 or 2 , wherein the second elastic member is a resin ring member.

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